1. Field of the Invention
The present invention relates to a scanning exposure apparatus, a control apparatus, and a method of manufacturing a device.
2. Description of the Related Art
An exposure apparatus projects the pattern of an original (reticle) onto a substrate (for example, a wafer or a glass plate) by a projection optical system to expose the substrate. The substrate is coated with a photosensitive material (photoresist). The pattern of the original is transferred onto the photosensitive material as a latent image pattern by exposing the photosensitive material. The latent image pattern is developed into a physical pattern (resist pattern) through a development process. To transfer the pattern of the original onto the substrate, alignment between the original and the substrate is of prime importance. The original is supported by an original stage having an original chuck, while the substrate is supported by a substrate stage having a substrate chuck. The original stage and the substrate stage are driven by driving mechanisms (for example, linear motors) (neither is shown). An exposure apparatus which exposes a substrate to light limited to a region smaller than a shot region while moving both an original and the substrate is called a scanning exposure apparatus (or a scanner). The scanning exposure apparatus must scan the original and the substrate while synchronizing them with each other so that their synchronization error falls below a target synchronization error.
Japanese Patent No. 3755862 (FIG. 4 and paragraph “0031”) discloses a synchronous position control apparatus applicable to, for example, a synchronous position control system for a wafer stage and a reticle stage. Japanese Patent No. 3755862 discloses an arrangement which obtains, as a synchronization error, the difference between the following position of a second position control means and a position obtained by multiplying the position of a first position control means by a coefficient K, and sends the synchronization error to the second control means via a synchronization correction means as a position command value.
The above-mentioned arrangement described in Japanese Patent No. 3755862 can lessen the influence that disturbance on a controlled object exerts on the synchronization error. Such control is called master-slave synchronization control. Unfortunately, in the master-slave synchronization control, the symmetry of response characteristics between axes deteriorates.